1. Field of the Invention
The present invention relates generally to an oil supply apparatus for vehicles and, more particularly, to a structure of the apparatus which supplies oil to a transmission in a vehicle having an ISG (Idle Stop & Go) function.
2. Description of Related Art
The function of ISG is an important technique in the development of environmental-friendly and high fuel efficient vehicles that has recently become a great topic of conversation. The ISG is a technique in which during stoppage of a vehicle, the operation of the engine stops to eliminate unnecessary fuel consumption while stopped.
Conventional vehicles having such an ISG function include an oil supply apparatus of FIG. 1 that supplies oil to a transmission. In detail, an engine 500 and an oscillator 502 are connected to a drive unit of a mechanical oil pump 504. While the engine 500 is being operated, the mechanical oil pump 504 pumps oil to supply it to a transmission 506. In an ISG state in which the engine 500 is stationary, a motor 508 is operated so that an electric oil pump 510 pumps oil to supply it to the transmission 506. Thereby, during the stoppage of the vehicle, standby oil pressure in the transmission 506 can be maintained so that when the vehicle restarts, the transmission 506 can be smoothly operated.
However, the conventional oil supply apparatus having the above-mentioned construction needs two oil pumps including the mechanical oil pump 504 and the electric oil pump 510 that have the same function of pumping oil to supply it to the transmission 506. Further, separate oil passages and a check valve 512 for backflow prevention, etc., are also required. Therefore, the number of parts increases, and the structure of the apparatus is complex.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.